FIG 2.

Phylogenetic analyses of the six internal genes of H4 avian influenza viruses isolated from live poultry markets in China between 2009 and 2012. Phylogenetic trees were generated by using the neighbor-joining method and the MEGA5.0 software package. The regions of nucleotide sequence used for the phylogenetic analyses were the following: PB2, 37 to 2289; PB1, 25 to 2233; PA, 25 to 2167; NP, 46 to 1526; M, 26 to 1007; and NS, 27 to 859. The phylogenetic trees of PB2 (A), PB1 (B), PA (C), NP (D), M (E), and NS (F) all were rooted to A/equine/Prague/1/1956 (H7N7). The phylogenetic branches of viruses sequenced in this study are colored in the phylogenetic tree based on the colors of their HA genes: blue, magenta, and green for groups 1, 2, and 3, respectively. Larger versions of these phylogenetic trees are provided in Fig. S1A to F in the supplemental material.